‘It is lovely and unusual to watch an entire romance develop across a novel’ … The Versions of Us author Laura Barnett. Photograph: Sarah Lee for the Guardian

Every couple has their “what might have been”. As a child I can still remember the dramatic thrill of my own potential nonexistence – my parents broke up as teenagers then ran into each other on the street years later. I met my husband on a holiday outing following a chance encounter on a Miami beach. Every one of us has many, many roads not taken.

And we know deep down how many unions are formed by good timing and suitability rather than random lightning bolts – otherwise, it would be statistically astonishing just how many people fall in love at the age of 28, at the same time as all their friends. Meanwhile, the appeal of wondering how life might have turned out had you stuck with somebody else can be seen in the astonishing numbers of Facebook citations in divorce petitions.

All of the above goes towards making this novel so much fun. The Versions of Us could be described as Sliding Doors, except with three stories instead of two; Life After Life, without all the messy deaths; or The Warlock of Firetop Mountain, without (slightly disappointingly) a big fire-breathing dragon.

In version one, Eva and Jim meet and fall in love at university in the 1950s; in version two, they just miss one another; and in version three, it all goes horribly wrong.

It is an alternate universe romance: a book of missed chances, as the characters wind in and out of each other’s lives in a variety of ways. It is indisputably a novel that demands to be read physically rather than in e-reader form. You’ll want to skip forward to follow each individual strand (a handy trick is to remember the first baby if you can).

At its best, the novel is reminiscent of Elizabeth Jane Howard’s glorious Cazalet Chronicles, with the same casual metropolitan wealth and romantic intrigues. It may be a little careless around the edges – could you really park a child in front of the television all day in 1966? Would Eva have had a word processor at home in 1977? – while supporting characters such as Penelope, Eva’s best friend, or Miriam, her saintly mother, are not so much sketchy as parsimonious ink dots.

But the twists and turns of the central characters will keep you engrossed, the novel is very readable, and I thoroughly enjoyed the portrayal of the heroine Eva, an introverted, self‑contained woman one cannot help liking. The appeal of Jim, apart from his purply eyes, was rather harder to spot, while pretty, selfish David, Eva’s occasional alternate life partner, is far more fun: I could have done with rather more of him.

While the book is not as gut-wrenching as David Nicholls’s One Day, it is an unusual and lovely thing to watch an entire romance develop across a novel, not just the fun early bits, or unpleasant midlife startings-over, or male midlife crises disguised as literary novels. Its very scope is a joy, the technical achievement seamlessly done, and the ending – all the endings – suitably affecting, regardless of how winding the route one takes to get there. Your patience will be rewarded in more ways than one.

•Resistance Is Futile by Jenny T Colgan is published by Orbit. To order The Versions of Us for £9.99 (RRP £12.99) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.